How interesting. Restaurant refuses to serve customer because customer does not tip.
1. If a tip is required, is it a tip?
2. Can restaurants refuse to serve someone, based on the refusal to pay a voluntary gratuity? After all, the restaurant could add 18% to its price, and give the extra money to the servers/table chef (it's one of those "Japanese Steakhouse" places with a mostly Latino staff).
3. Isn't a petition, and public scorning, the right thing for the customer to do, if she disagrees.
2. Yes, but then I think a private restaurant can refuse to serve anyone, at any time, for any reason. What part of "private" don't you understand?
(Nod to Anonyman, who even tips at Locopop, because he is washed in the milk of human kindness, even though that took a LOT of milk)